Using FLD damage for sheet metal forming in Abaqus

This video explains how to use Forming Limit Diagram (FLD) in Abaqus to predict damage of sheet metal forming.
In this video deep drawing of a box is modeled using shell elements and damage initiation using FLD, damage evolution and element deletion are described. In this video you can find out:
How to create elastic and plastic behavior of metals?
How to create damage initiation criteria for metals based on FLD?
How to create damage evolution rule for metals?
How to model damage of metals?
How to use FLD damage in Abaqus?
How to define element deletion in Abaqus?
How to hide some parts in Abaqus?
How to request and plot FLDCRT in Abaqus?
What are available damage outputs of FLD?

[@salahlaboubi9201]

Thank you so much. Can you please tell me how to draw the FLD curve using field output?

[@hnrwagner]

great video, thanks. I am not sure how to request the FLDCRT variable. I have activated DMICRT, but FLDCRT doesnt show up in the result visualisation

[@engineering_software]

Thanks, maybe the material definition is not complete.

[@yunsongguo584]

The models for sheet metal necking instability (FLD, FLSD, MSFLD, and M-K) are available only with elements that include mechanical behavior and use a plane stress formulation (i.e., plane stress, shell, continuum shell, and membrane elements).

[@juancarlosalvaradomorones764]

How did you manage to plot the FLDCRT value on the Model Part in ABAQUS//CAE? I've ran an Abaqus/Explicit Simulation where I request FLDCRT as History Output (as indicated from the Abaqus Documentation) for an element set, it does calculate it but the only thing I can get out of it is to plot a XY plot Time-FLDCRT for each element. I cannot manage to visualize in any other way the FLDCRT over the structure in ABAQUS/CAE since it's not a Field Variable.
Any hint on what's the key setting to be able to plot it as shown in the video? Many thanks!

[@yunsongguo584]

The models for sheet metal necking instability (FLD, FLSD, MSFLD, and M-K) are available only with elements that include mechanical behavior and use a plane stress formulation (i.e., plane stress, shell, continuum shell, and membrane elements).

[@sianourani1042]

great work! I can see your second plastic strain is 0.35. is it extrapolation of your graph? or UTS point or fracture point? could we use FLD diagram for a solid-3D-deformable-extrusion sheet?

[@engineering_software]

It is UTS point, and you can find the complete curve in JCARME Vol. 4, No. 2, Spring􀀐2015 pp121-132.
At first the value is true stress and be sure to enter true stress-strain curve. especially after onset of necking computing true stress is not straightforward.
If damage in biaxial loading happens before this strain you have no problem but if damage happens after that point the software extrapolate this value.

[@engineering_software]

FLD, MSFLD, and M-K criteria can be used only in plane stress condition. in bulke metal forming or any kind of simulation with 3D elements Ductile and/or shear damage can be used.

[@sianourani1042]

@@engineering_software thanks for your explanation. unfortunately finding ductile damage parameters is quite difficult ( they are only available for few materials). so I am trying to apply FLD damage in my model. however, it seems that It can not be used for the axisymmetric model, right? my simulation is 2D axisymmetric and the thickness of sheets is highly important.

[@sianourani1042]

thanks a lot for your positive response. after UTS point, I have used swift law to extrapolate the stress and strain up to 100% but I am not sure if it is the right way?

[@engineering_software]

This model is applicable to the plane stress condition including 2d problems and shell problems.

[@rakeshbose6280]

Sir how you calculated the energy for damage evaluation

[@duonghoang6855]

Thank you, I have a question. " Do we need to add the damage evolution into FLD damage?"

[@engineering_software]

FLD is a damage initiation criterion and can predict onset of damage. to predict material degradation after onset of damage we need to add a damage evolution rule.

[@duonghoang6855]

@@engineering_software Yes, How do we know the damage evolution value of each material?

[@duonghoang6855]

@@engineering_software How can I know frature energy or displacement at failure?

[@mahmoudmokadem7128]

Great Work! but mine won't fracture and I don't know the reason, could you help me?

[@yunsongguo584]

The models for sheet metal necking instability (FLD, FLSD, MSFLD, and M-K) are available only with elements that include mechanical behavior and use a plane stress formulation (i.e., plane stress, shell, continuum shell, and membrane elements).

[@aouiched9613]

Very interesting information, but I have a problem with damage in my model I send you an email about if you can advise me thanks

[@engineering_software]

What is it?

[@aouiched9613]

@@engineering_software I'm trying to model the fracture of the bolt in beam-column connection
i just have the stress-strain curve and i found this information in a PhD thesis :
In ABAQUS,
material fracture and failure can be explicitly defined for metals by defining appropriate
damage initiation and damage evolution criteria, which simulates the ductile fracture
of metals via void nucleation and growth (ABAQUS, 2013). However, in the absence
of relevant material parameters, a simplified approach was followed, according to which
fracture of the components was not explicitly modeled but was indirectly defined based on
the uniaxial plastic strain at fracture εf
how can exploit that? knowing that another Ana Gerao Coelho uses Ultime strain instead of plastic strain
thanks

[@engineering_software]

I answered it in email.

[@aouiched9613]

@@engineering_software yes thanks, I know what the authors mean but the problem how to exploit that in Abaqus? should I use ductile damage or other criteria?

[@engineering_software]

In fact, they did not use any damage criteria and just inserted stress-strain curve including the softening part of the curve.